JP3057681B2 - Switching circuit for horizontal S-shaped correction capacitance - Google Patents

Description

The present invention relates to a horizontal S-shaped correction capacitance switching circuit suitable for use in a horizontal deflection device for a multi-scan television receiver according to the present invention.

[Summary of the Invention]

The present invention relates to a switching circuit for a horizontal S-correction capacitor of a horizontal deflection device for a multi-parallel television receiver, wherein a semiconductor switching element connected to an S-correction capacitor having a predetermined potential with respect to a ground point is connected to a photocoupler. The S-shaped correction capacitance is switched by using a semiconductor switching element without using a relay under the control of a DC voltage, and the horizontal S-shaped correction capacitance is switched.

[Conventional technology]

Conventionally, for example, in an NTSC system television signal, an image is formed at a vertical frequency of about 60 Hz and a horizontal frequency of about 15.75 kHz. There has been proposed a conversion device that improves the image quality to be obtained. When this device is used, the signal to be output has a vertical frequency of about 60 Hz and a horizontal frequency of about 31.5 kHz.

In addition, there is an output signal of a so-called high-resolution display personal computer having a horizontal frequency of about 24 kHz. In a so-called high-definition television, the horizontal frequency is about 33.75 kHz.

A multi-scanning television receiver has been proposed which enables a single apparatus to receive various video signals having different horizontal frequencies.

FIG. 3 shows an example of this multi-scan television receiver. In FIG. 3, when receiving a normal composite video signal from a tuner for receiving a normal television broadcast or a video tape recorder, a video disc player, some personal computers, or the like, the signal is supplied to the input terminal (1). The resulting composite video signal is supplied to an RGB process circuit (3) through a video process circuit (2) to form three primary color signals of a red signal R, a green signal G, and a blue signal B. Video RG supplied to input terminal (4)
The switching signal of B is supplied to the process circuit (3), whereby the three primary color signals from the selected video signal are supplied to the color cathode ray tube (6) through the output circuit (5).

Further, the composite video signal from the input terminal (1) is supplied to the synchronization separation circuit (7), and the vertical and horizontal synchronization signals are separated. Further, the switching signal from the input terminal (4) is supplied to the synchronization separation circuit (7), whereby the vertical synchronization signal of the selected video signal is supplied to the vertical deflection circuit (8), and the formed vertical deflection signal is It is supplied to a vertical deflection coil (9) of a color cathode ray tube (6). Synchronous separation circuit (7)
The horizontal sync signal of the video signal selected in step 2 is the AFC circuit (10)
The signal from the AFC circuit (10) is supplied to the horizontal oscillation circuit (11) and the mode detection circuit (12)
Is supplied to the horizontal oscillation circuit (11). The signal from the horizontal oscillation circuit (11) is supplied to the horizontal deflection circuit (13), and the formed horizontal deflection signal is supplied to the horizontal deflection coil (14) of the color cathode ray tube (6). Further, a signal from the horizontal deflection circuit (13) is supplied to a high voltage generation circuit (15) such as a flyback transformer, and the generated high voltage is applied to a high voltage terminal (1) of the color cathode ray tube (6).
6) and a part of the signal is supplied to the AFC circuit (10).

Further, commercial power from the power input terminal (17) is supplied to the power circuit (18), and a normal voltage corresponding to a signal from the mode detection circuit (12) is supplied to the horizontal deflection circuit (13). Also, commercial power from the power input terminal (17) is supplied to another power supply circuit (19), and the voltage generated thereby is supplied to another circuit.

As a result, a normal composite video signal is received.
On the other hand, when receiving the three primary color signals of digital or analog red, green and blue signals from some personal computers, so-called captain doubletoners, teletext doubletoners, scan conversion devices, etc. Terminal (20R) (20
G) The digital RG and B signals supplied to (20B) and the analog signals supplied to the input terminals (21R) (21G) (21B)
RG and B signals are selected by the changeover switch (22) and RGB
It is supplied to the process circuit (3), selected by the switching signal from the input terminal (4), and supplied to the output circuit (5).

In addition, the digital R, G, and B synchronization signals from the input terminal (20S) and the analog R, G, and B synchronization signals from the input terminal (21S) are selected by the changeover switch (23) and synchronized. The signal is supplied to the separation circuit (7), selected by the switching signal from the input terminal (4), and supplied to the vertical deflection circuit (8) and the AFC circuit (10). Further, a signal from the synchronization separation circuit (7) is supplied to a mode detection circuit (12), and a control signal corresponding to the frequency of the horizontal synchronization signal is formed to form a horizontal oscillation circuit (11), a horizontal deflection circuit (13), and a power supply. It is supplied to the circuit (18).

As a result, digital or analog R, G and B signals of three primary colors are received.

Image reception of various signals is performed as described above. Further, in the above-described apparatus, the horizontal deflection system is specifically configured as shown in FIG. In FIG. 2, a horizontal synchronization signal from a synchronization separation circuit (7) is supplied to a horizontal synchronization signal input terminal (7).
H) via the frequency which constitutes the mode detection circuit (12)
The voltage is supplied to the voltage transformation circuit (31) to form a voltage according to the horizontal frequency. As this frequency-voltage conversion circuit (31), for example, a horizontal synchronizing signal from a horizontal synchronizing signal input terminal (7H) is supplied to a mono-multivibrator having a predetermined time constant, and an output signal of the mono-multivibrator is used for smoothing. The voltage is supplied to a low-pass filter so that a voltage corresponding to the horizontal frequency is obtained at an output terminal. This voltage is supplied to a voltage controlled variable frequency oscillator (hereinafter referred to as VCO) (34) constituting the horizontal oscillation circuit (11) through a limiter circuit (32) and a buffer amplifier (33) which determine the lower limit. This VCO (3
The oscillation output of 4) is supplied to the switching transistor (36) constituting the horizontal deflection circuit (13) through the drive circuit (35).

Further, the voltage from the frequency-voltage conversion circuit (31) determines the upper and lower limits through a limiter circuit (37) and a control amplifier (38) to form a power supply circuit (18), for example, a YZ type parametric power supply circuit (39). Supplied. This power circuit (3
9) The output voltage of the control amplifier (3
8) and the output voltage is stabilized. This output voltage is supplied to the flyback transformer (41).

A horizontal output transistor (36) is connected in series to the flyback transformer (41). Two series-connected damper diodes (42a) and (42b), two series-connected resonance capacitors (43a) and (43b), and a horizontal deflection coil (14) and S-shaped correction in parallel with the transistor (36). A series circuit of a capacitor (44a) and a pincushion modulated coil (hereinafter referred to as PMC) (48) is connected. Further, the series connection point of the resonance capacitors (43a) and (43b) and the series connection point of the damper diodes (42a) and (42b) are short-circuited, and the series connection point of the resonance capacitors (43a) and (43b) and the S-shape. Correction capacitor (44a) and PMC (4
8) and a second S-shaped correction capacitor (44
b) is connected, and the S-shaped correction capacitors (44a) (44
S-shaped correction capacitors (49a) and (49b) connected in series with switching means (50a) and (50b), which are relays according to the horizontal frequency range, are connected in parallel to b).

A pulse voltage is output to the pin distortion correction circuit from between the series connection point of the resonance capacitors (43a) (43b) and one end of the S-shaped correction capacitors (44b) (49b). Further, the voltage from the frequency-voltage circuit (31) is, for example, 20 Hz of the input horizontal frequency.
The comparison output is supplied to a comparison circuit (54) for binary comparison corresponding to a voltage of kHz, and a comparison output corresponding to a range of 20 kHz or less, 20 to 30 kHz, or 30 kHz or more is formed, and switching means (50a ) (50b) is turned “ON” and “OFF”, and the S-curve correction characteristic is corrected in accordance with the horizontal frequency range.

The horizontal synchronizing signal is supplied to a detection circuit (45) constituting the AFC circuit (10) shown in FIG. 3, and is supplied from a voltage dividing circuit (46a) (46b) provided in parallel with the transistor (36). The signal is supplied to a detection circuit (45), and an AFC signal is formed. This signal is supplied to the control terminal of the VOC (34) through the low-pass filter (LPF) (47).

[Problems to be solved by the invention]

As shown in the above-described conventional configuration, the S-shaped correction capacitors (44a), (44b), (49a), and (49) are used in the switching circuit of the horizontal S-shaped correction capacitance of the horizontal deflection device for a multi-scan television receiver.
Since the switching means (50a) and (50b) cannot use a semiconductor switching element because b) has a predetermined potential ea with respect to the ground potential, _a relay is used. When such a relay is used, not only when the power switch is disconnected and connected, but also when the number of horizontal frequencies of the input signal changes, not only the relay switching sound is heard, but also the response is slow, and the response is slow. There were drawbacks such as a rise in temperature.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described drawbacks, and has as its object to provide _a horizontal switching element that can use a semiconductor switching element even when one end of an S-shaped correction capacitor has _a predetermined voltage ea with respect to a ground potential. An object of the present invention is to provide an S-shaped correction capacitance switching circuit.

[Means for solving the problem]

A horizontal S-shaped correction capacitance switching circuit according to the present invention is a horizontal S-shaped correction capacitance switching circuit of a horizontal deflection device for a multi-scan television receiver, wherein the horizontal S-shaped correction capacitance switching circuit is connected in series with a flyback transformer (41). First and second damper means (42a) and (42b), which are connected in series with the flight back lance (41) of the output means (36) and whose other ends are grounded, are connected in series with the flyback transformer (41); First and second resonance capacitors (43a) and (43b) having the other ends grounded, and a flyback truss (41)
A first series circuit including a horizontal deflection inductance (14), a first correction capacitance (44a), and a distortion correction inductance (48) connected in series with the first correction capacitance ( 44a) a second correction capacitor (49a) and a switching first active element (51a) connected in parallel with each other.
A second series circuit comprising first and second damper means (42a) (42b) and first and second resonance capacitors (43
a) The correction point connected between the connection point between the series connection point of (43b) and the connection point between the first correction capacitance (44a) and the distortion correction inductance (48) which is made higher than the ground potential. A third capacitor (44b), a fourth capacitor (49b) for correction connected in parallel with the third capacitor (44b) for correction, and a second active element (52b) for switching. 3, an active element (57) to which high and low DC voltages are supplied corresponding to a plurality of different input horizontal frequencies, and an ON / OFF control of the first and second active elements (57). Light receiving element (56)
Optical coupling means (55) comprising:
The first and second active elements (51a) and (51b) are switched and controlled through the output of the light receiving element (56) of (5).

[Action]

According to the horizontal S-correction capacitance switching circuit of the present invention, the switching element is connected and disconnected by using the H or L DC voltage via the photocoupler (55). Since a switching element can be used, a switching circuit with high responsiveness that does not generate noise or cause contact welding can be obtained.

〔Example〕

Hereinafter, a switching circuit for the horizontal S-shaped correction capacitance used in the horizontal deflection device of the multi-scan television receiver according to the present invention will be described with reference to FIG. In FIG. 1, the third
Parts corresponding to those in FIG. 2 and FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted. In this column, the difference from the configuration shown in FIG. 2 is that the comparison circuit (54) and the horizontal deflection circuit (1
3) Part. First, the comparison circuit (54) outputs a high (H) or low (L) DC voltage corresponding to the input horizontal frequency of the horizontal synchronizing signal, and is supplied to the light emitting element (57) of the photocoupler (55). . The light receiving element (56) of the photocoupler (55) is connected to the secondary side (41) of the flyback transformer (41).
The voltage taken from b), the DC voltage e _b is supplied with rectified by diode 53 and capacitor (58).
That is, the secondary coil (41) of the flyback transformer (41)
b) Connect a capacitor (58) in parallel with a diode (5
3) Connect in series, connected S-correction capacitor to the other end a predetermined voltage e _a collector of one light receiving element of the capacitor (58) (56) has been applied and (44a) to the intersection of the PMC (48) I do. Further, one end of the emitter resistor (60) of the light receiving element (56) of the photocoupler (55) is connected to the other end of the resistor (60), and the other end of the resistor (60) is connected to the other end of the capacitor (58).

Further, the switching means (50a) (50b) connected in series to the S-shaped correction capacitors (49a) (49b) are semiconductor switching elements, for example, FETs (51a) (51b).
In (51a) and (51b), backflow prevention diodes (52a) and (52b) are connected in parallel between the source and the drain.

The gates of the FETs (51a) and (51b) are connected from the connection point A between the resistor (60) and the emitter of the light receiving element (56) to the resistor (59).
Is supplied with the voltage.

In the above-described configuration, for example, a DC voltage of H or L is applied from the comparison circuit (54) to the light emitting element (5
7), the light receiving element (5
Potential e _a 6) side of the point A H '= e _b, L' so that it can FET (51a) (51b) may be connecting and disconnecting by the H 'or L'. This allows the S-shaped correction capacitors (44a) (44b) (49a) (49b)
For example, even when connected to e _a , switching can be performed with only the H or L DC voltage with respect to the ground point, so that a semiconductor switching element can be used as the switching means.

In the above embodiment, an insulated gate transistor (FET) is shown as a switching element, but a P or N channel enhancement type field effect transistor or a PN
A P or NPN transistor or the like can be used.

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

〔The invention's effect〕

According to the switching circuit of the horizontal S-shaped correction capacitor of the present invention, the semiconductor switching element can be connected and disconnected via the photocoupler even if the S-shaped correction capacitor has a predetermined potential with respect to the ground potential. It is possible to obtain a switching circuit that is fast and free from noise generation and contact welding.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a switching circuit for a horizontal S-shaped correction capacitor according to the present invention, FIG. 2 is a circuit diagram showing a conventional switching circuit for a horizontal S-shaped correction capacitor, and FIG. FIG. 2 is a system diagram illustrating a scanning television receiver. (13) is a horizontal deflection circuit, (50a) and (50b) are switching means, (51a) and (51b) are FETs, and (55) is a photocoupler.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-157568 (JP, A) JP-A-61-96875 (JP, A) JP-A-63-28176 (JP, A) JP-A-63-15776 56070 (JP, A) JP-A-60-6990 (JP, A) JP-A-62-254575 (JP, A) JP-A-1-2822971 (JP, A) JP-A-52-5320 (JP, A) Japanese Utility Model Showa 62-99097 (JP, U) Japanese Patent Publication 58-2504 (JP, B2)

Claims (1)

(57) [Claims] In a switching circuit for a horizontal S-shaped correction capacitance of a horizontal deflection device for a multi-scanning television receiver, a horizontal output means connected in series with a flyback transformer is connected in series with the flyback transformer. First and second damper means having the other end grounded, first and second resonance capacitors connected in series with the flight back lance, and the other end grounded, and connected in series to the flyback transformer A first DC circuit comprising the horizontal deflection inductance, the first correction capacitance, and the distortion correction inductance, and a second correction capacitance connected in parallel with the first correction capacitance. A second series circuit comprising a first active element for switching; a series connection midpoint between the first and second damper means and the first and second resonance capacitors; A third capacitance for correction connected between the connection points between the first correction capacitance and the distortion correction inductance formed at a potential, and a third capacitance for correction connected in parallel to the third capacitance for correction. A third series circuit including a fourth correction capacitor and a second active element for switching, a light emitting element to which high and low DC voltages are supplied corresponding to a plurality of different input horizontal frequencies; An optical coupling means comprising a light receiving element capable of controlling ON and OFF of the first and second active elements, wherein the first coupling means comprises a main element of the light receiving element of the optical coupling means.
And a switching circuit for a horizontal S-shaped correction capacitor, which is configured to switch and control the second active element.